ES2429491T3 - Safety device and micromachining or microgravure weaponry - Google Patents

Abstract

Security and armament device (12) micromachining or microgravure for a pyrotechnic chain of a projectile (1) which is provided at the time of firing of an axial rotation movement, device comprising a substrate (13) on which a shutter is arranged (14) pyrotechnic chain interruption which is mobile in translation on the substrate (13), a device in which the chain interruption shutter (14) keeps immobilized by at least two locks (17, 22), a first block (17 ), or axial acceleration block, which is released after the application of the acceleration communicated to the projectile (1) at the time of firing and a second block (22), a device characterized by the fact that the second block (22) is a centrifugal block which is released after the rotation of the projectile (1) and by the fact that the centrifugal lock comprises at least one locking pin (22) attached to the substrate (13), a pin that is supported on a groove (24) of the shutter (14) when it occupies its locking position, maintenance is ensured by a micromachining counterweight (26) which is slidably mounted in a housing (25) of the shutter (14).

Description

Safety device and micromachining or microgravure weaponry

[0001] The technical field of the invention is that of safety and armament devices for a pyrotechnic chain of a projectile and particularly of micromachined safety and armament devices.

[0002] Security devices (or DSA) are well known. They usually have a screen that blocks a transmission channel that connects a detonator and a pyrotechnic charge.

[0003] The screen thus interposes on the transmission of the detonation wave between the detonator and the load and prevents the latter from operating.

[0004] One of the problems posed by traditional devices is their congestion. The pieces are relatively massive in order to ensure the interruption of the pyrotechnic chain. The motor means that allow the screen to move must therefore be powerful. Most of the times, springs that are tensioned throughout the storage phases are used, which can lead to a degradation of their mechanical characteristics and a loss of armament reliability.

[0005] For some years it has been proposed to make all or part of the safety devices with the help of chips that incorporate micro-machined or micro-etched electromechanical elements, either in an element deposited on a substrate or directly on the substrate itself. This technology known under the name of MEMS (Micro Electro Mechanical System) allows today to perform micro-mechanisms that use a technique similar to that which allows electronic integrated circuits.

[0006] US-6167809 describes a miniature device, according to the preamble of claim 1, which also uses MEMS technology, but in which the second lock is driven by acceleration and not by centrifugal force. A first block is released by a counterweight that under the effect of acceleration will move in the opposite direction against the action of a spring, will unlock this first block and will be fixed in a stopping means. The second lock is disengaged from a latch 59 and is set in motion by an actuator not shown, consisting of a pyrotechnic composition inserted in a channel. As indicated in this patent, the second block moves forward without any effect of centrifugal force.

[0007] US-6964231 discloses a micromachined safety device that comprises a shutter that has a pyrotechnic charge and slides by the action of the centrifugal force. This shutter is immobilized by a blockage that is eliminated by the projectile's acceleration.

[0008] Another tilt lock allows the shutter to be released that is brought to its armed position by centrifugal inertia force. The rocker block is actuated by a pyrotechnic gas generating composition whose ignition is activated by an electronic means.

[0009] Such a safety and armament device allows two independent environmental conditions to be used to secure armament: longitudinal firing acceleration and centrifugal acceleration. This double security allows this device to comply with the most stringent rules on the safety of projectile weapons (STANAG 4187).

[0010] However, it is of complex structure and particularly the second block (tilt block) requires the use of a pyrotechnic composition as well as initiation means thereof. An electronic system must, therefore, be designed to pilot the operation of this MEMS that is poorly adapted for use in medium-sized ammunition (caliber less than 40 mm) for which the available volume is limited.

[0011] The aim of the invention is to propose a micromachining and safety device with a simple structure and that meets the most demanding safety conditions, particularly requiring the presence of two independent environmental conditions to move to an armed position.

[0012] The device according to the invention applies a 100% mechanical armament while ensuring a reliable interruption of the pyrotechnic chain.

[0013] Thus, the invention has as its object a safety device and micromachined armament

or microgravure for a pyrotechnic chain of a projectile that is provided, at the time of firing, of an axial rotation movement, a device that includes a substrate on which a pyrotechnic chain interruption shutter is arranged that is mobile in translation over the substrate, a device in which the chain interrupt shutter is held immobilized by at least two locks, a first block (or axial acceleration block) that is released after the acceleration application communicated to the projectile at the time of firing and a second block, device characterized by the fact that the second block is a centrifugal block that is released after rotation of the projectile, and by the fact that the centrifugal block includes at least one locking pin attached to the substrate, a pin that is supported in a groove of the shutter when it occupies its locked position, maintenance is ensured by a counter Micromachined centrifugal weight that is slidably mounted in a shutter housing.

[0014] The centrifugal counterweight will be slidably mounted against the action of a first elastic means.

[0015] Brake means may be provided to slow the movement of the counterweight.

[0016] The shutter may advantageously slide by the action of the centrifugal force and against the action of a second elastic means.

[0017] The locking pin may be attached to the substrate by means of a flexible tongue.

[0018] According to a particular embodiment, the brake means may comprise sheets attached to at least one of the flexible tabs, sheets that rub against a lateral surface of the counterweight.

[0019] The substrate will advantageously involve a hole in both parts of the plug, the axis of these holes, therefore the direction of action of the pyrotechnic chain, is substantially parallel to the plane of the plug.

[0020] The invention will be better understood with the following descriptive reading of a particular embodiment, description made with reference to the attached drawings and in which:

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 Figure 1 is a schematic sectional view of a medium caliber projectile equipped with a rocket incorporating a safety and armament device according to the invention,

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 Figure 2 is a view of an embodiment of the security and weapon device according to the invention in its safety position,

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 Figures 3a, 3b and 3c show this same device along different stages that lead to its armament.

[0021] Figure 1 shows a projectile 1 of medium caliber (caliber less than 50 mm), comprising a body 2 containing an explosive charge 3. The body 2 receives in its front part a rocket 4 that is screwed into a thread of the body 2. The rocket 4 includes a housing 8 containing a detonating charge 5. The detonating load 5 is intended to be initiated by a pyrotechnic chain that includes a detonator 6 and a relay 7 (alternatively this relay 7 could be omitted and the detonator 6 will then directly initiate the detonating charge 5). The detonator 6 is here a percussion detonator that is started by a firing pin 9 slidably installed in a nose 10 attached to the housing 8 of the rocket 4. At the moment of the impact of the projectile 1 on a target, the firing pin 9 is projected on the detonator 6. The firing pin is held in position during the storage and firing phases by a shear washer 11.

[0022] Of course, it is possible to start the device according to the invention with an electric detonator 6 operated for example by an electronic means of chronometry or a proximity detector.

[0023] The rocket 4 also contains a safety and armament device 12 which allows the pyrotechnic chain to be interrupted throughout the storage and firing phases of projectile 1.

[0024] According to the invention, this safety and armament device is made in the form of a micromachining or microgravure device (MEMS). It thus includes a substrate 13 on which a sliding shutter 14 is installed that ensures the interruption of the pyrotechnic chain.

[0025] The substrate 13 includes two holes 15a and 15b arranged in both parts of the shutter 14. The axis of these holes 15a, 15b, therefore the direction of action of the pyrotechnic chain (6-7), is, of this mode, considerably parallel to the shutter plane 14.

[0026] This type of arrangement of a pyrotechnic chain interrupt shutter such that the direction of the pyrotechnic chain is in front of the thickness of the shutter 14 and not perpendicular to the plane of the shutter (as in usual MEMS devices) is Particularly aware of the patent EP1780496.

[0027] The person skilled in the art will refer to this patent which describes the general characteristics of such a type of detonator chain and the obturator that is associated with it.

[0028] In this mode, we observe that the detonator 6 must have the minimum size that allows to ensure the operation and will be coupled to an appropriate pyrotechnic relay 7 (or 5). It has been verified that by starting a detonator that involves an output stage of 10 milligrams of hexogen coupled to a very little sensitive relay, for example in HNS (hexanitrostilbeno), it was possible to make holes 15a, 15b (or transmission channels ) of less than 1 mm2 section (channel diameter of the order of mm) while guaranteeing the desired initiation transmission.

[0029] In this way it is possible to ensure an interruption of the pyrotechnic effect with a silicon plug having a length L of the order of 3 mm, which is fully realizable with MEMS technologies. This silicon length of the order of 3mm therefore corresponds in this case to the dimension L of the plug 14 shown in Figures 1 and 2.

[0030] The projectile 1 is also provided with a belt 2a that takes the striations of the weapon tube (not shown) and that communicates to the projectile 1 a rotation movement around its axis at the time of firing.

[0031] Figure 2 shows in more detail the internal structure of the safety device 12 according to the invention.

[0032] The device therefore includes a substrate 13 on which a pyrotechnic chain interruption shutter 14 is disposed that is movable in translation on the substrate.

[0033] The shutter 14 is made by micromachining or micro recording, according to MEMS realization techniques that are well known to those skilled in the art.

[0034] The holes 15a and 15b that are arranged in both parts of the plug 14, as well as the axis 16 of these holes (hence the direction of action of the pyrotechnic chain) have been shown in the figures. The dimension L of the shutter 14 ensures the interruption of the pyrotechnic chain in the safety position of the device 12.

[0035] The chain interrupt shutter 14 is held immobilized by two locks.

[0036] A first block 17 (or axial acceleration block) and a second block which is a centrifugal block released after projectile 1 rotation.

[0037] Thus, unlike the device known from US6964231 that requires a tilting lock actuated by a specific pyrotechnic composition, the device according to the invention directly uses the centrifugal inertia to open the shutter 14 while maintaining safety trajectory start (no weapons before a certain distance traveled outside the tube).

[0038] The first lock 17 cooperates with a notch 18a having a rod 18 attached to the shutter 14.

[0039] This block 17 is held in the rod 18 by an elastic means 19 interposed between the block 17 and the substrate 13.

[0040] The lock 17 also has a pin 20 having at least one slit. This pin 20 is intended to cooperate with a complementary cavity 21 which has the substrate to ensure immobilization of the first lock 17 in its open position.

[0041] The elastic means 19 is also made according to the micromachining or micro-recording technologies (MEMS technologies). The mechanical characteristics of the elastic means 19 are chosen so that the lock 17 is only released after the efforts related to the firing acceleration of the projectile 1. This block must, instead, remain in its locked position when subjected to the stresses. related to the manipulations or falls of the projectile.

[0042] The centrifugal lock includes at least one locking pin 22 that is attached to the substrate 13.

[0043] The device here includes two pins 22 made in the form of micromachined or micro-engraved cylindrical discs and attached to the substrate 13 by means of flexible tabs 23, these are also micromachined or micro-engraved.

[0044] Each pin 22 is housed in a groove 24 in a complementary manner and is located in a housing 25 of the plug 14.

[0045] In the locked position shown in Figure 2, the pins 22 are held in the slots 24 by a micromachining or microgravure centrifugal counterweight 26 which is slidably mounted with respect to the substrate 13 and in the housing 25 of the plug 14.

[0046] The counterweight 26 is held in its locked position (Figure 2) by a first elastic means 27 (also micromachining or microgravure). Of course, the mechanical characteristics of the first elastic means 27 are chosen so that the counterweight 26 only moves after the stresses related to the centrifugal acceleration resulting from the rotation of the projectile 1 at the time of firing. The counterweight must, instead, remain in its locked position when it is subjected to stresses related to manipulations or falls of the projectile.

[0047] The substrate 13 has a pin 28 having at least one slit. This pin 28 is intended to cooperate with a complementary cavity 29 which has the counterweight 26 to ensure an immobilization of the counterweight 26 in its open position.

[0048] The shutter 14 is slidably installed in a housing 30 of the substrate 13. Once the locks 17, 22 have been removed, the shutter 14 can slide in this housing 30 by the action of the centrifugal force and against the action of a second elastic means 31 (formed here by two parallel springs).

[0049] Finally, brake means are provided to slow the movement of the counterweight 26.

[0050] These means comprise sheets 32 that are attached to the flexible tongues 23 and that rub against the lateral surfaces 33 of the counterweight 26 (surfaces that could eventually have roughness or roughness). The brake means allow the movement of the counterweight 26 to be slowed down, therefore slowing down the removal of the centrifugal locks 22. This ensures mouth safety at the time of firing. The armament of the device 12 will only intervene after a certain distance has elapsed after the exit of the weapon tube.

[0051] The operation of this device will be described below with reference to Figures 3a to 3c.

[0052] Figure 3a shows the device in the position it adopts inside the gun tube at the time of firing.

[0053] The firing acceleration causes the appearance of an axial inertia force Fy on the first block 17. This block therefore releases the shutter 14. The block 17 remains immobilized in its open position by the effort of the pin 20 in the cavity 21.

[0054] The shutter 14 remains, however, in the safe position by the centrifugal lock 26/22.

[0055] In fact, the rotation speed is not yet sufficient to cause the separation of the counterweight 26. The interruption of the pyrotechnic chain by the shutter 14 is then always guaranteed.

[0056] Figure 3b shows the device in the position it adopts after its exit from the gun tube and at a distance of about fifty meters.

[0057] Centrifugal acceleration has caused the appearance of a radial inertia force F1W that is exerted on the counterweight 26. The counterweight has been progressively separated against the action of the second elastic means 27 and has been slowed by the friction of the sheets 32 on the lateral surfaces 33 of the counterweight 26.

[0058] The stiffness of the elastic means 27 and the brake means 32, 33 are defined to delay the passage of the counterweight 26 to its open position, so that the configuration according to Figure 3b only intervenes about fifty meters from the weapon tube . Security is then optimal for weapon users.

[0059] Once the counterweight 26 is closed in this position by the latch of the pin 28 in the complementary cavity 29, the centrifugal locks 22 are no longer maintained by the counterweight 26 (which also includes anterior bevel profiles 34 that facilitate the release of locks 22).

[0060] The shutter 14 is no longer immobilized by the locks 22 and can therefore assume its open position (Figure 3c).

[0061] It is also displaced by the effect of a centrifugal inertia force F2W and against the action of the second elastic means 31.

[0062] The movement of the shutter causes the loosening of the tabs 23 that the locks 22 have. The housing 25 is defined with sufficient depth to authorize the passage of the locks 22 between the counterweight 26 and the shutter 14.

[0063] Shutter 14 no longer seals holes 15a, 15b. The action direction 16 of the pyrotechnic chain is therefore released, and the device is in an armed position. An impact on a target will cause the explosive charge of the projectile to begin.

[0064] We will observe that the shutter 14 is closed in its armed position by the tabs 36 attached to the substrate 13 and that they engage in notches 37 arranged on a lateral surface of the shutter 14, so as to prohibit the return of the latter to its security position.

[0065] We see that the device according to the invention is extremely simple and not very bulky. It has a fully mechanical structure and can be incorporated into a medium caliber projectile at a lower cost.

[0066] The axis 35 behind which the counterweight 26 moves and the shutter 14 is perpendicular to the axis 16 of the direction of pyrotechnic action. When the device is installed in a projectile, the axis 35 therefore corresponds to a

10 radial direction of the projectile and centrifugal inertia may be exerted on the counterweight 26 and the shutter 14. The integration of the device into a projectile is therefore extremely simple, despite the reduced dimensions for this device 12. In fact, the alignment pyrotechnic axis 16 necessarily leads to a correct orientation of the device with respect to the projectile.

[0067] Various variants are possible without leaving the scope of the invention.

[0068] It is particularly possible to adopt different technical solutions for means 20/21, 28/29 that ensure the immobilization of the locks. The shapes of the elastic means may be different. They will be defined based on the firing restrictions that the projectile must suffer.

[0069] It is also possible to associate the safety and armament device according to the invention to an electric initiation detonator 6 coupled, for example, to an electronic means of chronometry or proximity detection.

Claims (7)

one.

 Safety and armament device (12) micromachining or microgravure for a pyrotechnic chain of a projectile (1) which is provided at the time of firing of an axial rotation movement, device comprising a substrate (13) on which it is arranged a pyrotechnic chain interruption shutter (14) that is mobile in translation on the substrate (13), a device in which the chain interruption shutter (14) is held immobilized by at least two locks (17, 22), a first block (17), or axial acceleration block, which is released after the application of the acceleration communicated to the projectile (1) at the time of firing and a second block (22), a device characterized by the fact that the second block (22) is a centrifugal lock that is released after rotation of the projectile (1) and by the fact that the centrifugal lock comprises at least one locking pin (22) attached to the substrate (13), a pin that is supported Taken in a groove (24) of the plug (14) when it occupies its blocking position, maintenance is ensured by a micromachined centrifugal counterweight (26) which is slidably mounted in a housing (25) of the plug (14).

2.

 Safety and armament device according to claim 1, characterized in that the centrifugal counterweight (26) is slidably mounted against the action of a first elastic means (27).

3.

 Safety and armament device according to claim 2, characterized in that the brake means (32) are provided to slow the movement of the counterweight (26).

Four.

 Safety and armament device according to one of claims 1 to 3, characterized in that the shutter (14) slides by the action of the centrifugal force and against the action of a second elastic means (31).

5.

 Security and armament device according to one of claims 1 to 4, characterized in that the locking pin (22) is connected to the substrate (13) by means of a flexible tongue (23).

6.

 Safety and armament device according to claims 3 and 5, characterized in that the brake means comprise sheets (32) attached to at least one of the flexible tabs (23), sheets that rub against a lateral surface of the counterweight (26).

7.

 Security and armament device according to one of claims 1 to 6, characterized in that the substrate (13) includes a hole (15a, 15b) in both parts of the plug (14), the shaft (16) of these holes, therefore the direction of action of the pyrotechnic chain, is substantially parallel to the plane of the plug (14).